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Discussion Starter · #1 ·
3 places for hose attachments on the petcock. Bike ran juuuuuuuuuuuuuust fine when it was all assembled, etc. Now, for reassembly (since i'm there now) I have a question. There were only TWO hoses hooked up- or even just there, for that matter. One was thicker, had the fuel filter attached- pretty obvious. So, what are the other ones? Why do I have two other places for smaller hoses, but only one small hose left over? I googled it, and found a diagram on the old CC site, but it was a diagram that didn't make much sense- it was just a picture. I can read all I want, and look at the pictures, and hear what part they go to.... but WHY was it running great, missing one hose? Guess I'm of the mindset that if it's there, it's there for a purpose and if it's supposed to be there, why should it be missing?



(the subject of appendix's drives me nuts! LOL)







Guess what I'm asking is- WTF is up with the vent hose??? Does it just hang out in the middle of nowhere?- pretty sure that's the one missing since it was running just fine without one... LOL
 

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Discussion Starter · #3 ·
right. I had edited this to show I knew vent, gas, and vac...... but if it NEEDS a hose for the vent line, why was it missing/ why have I not had any issues?
 

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right. I had edited this to show I knew vent, gas, and vac...... but if it NEEDS a hose for the vent line, why was it missing/ why have I not had any issues?
It probably doesn't need a hose but by having a hose it probably pulls air from and area that gets less crap. And if it did pick up some dirt it would be easier to clean.



Why do new atv and dirt bikes have vent hoses on their caps?
 

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Discussion Starter · #5 ·
Why do new atv and dirt bikes have vent hoses on their caps?




IDK they had them... lol... I've taken my brothers 4 wheeler out around the yard for about 15 minutes once. That's the most experience I've had with ATVs... haha
 

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In the event that the petcock fails, gas can come pouring out of the vent/drain port. The hose will direct the flow underneath the bike, in the same location as the carburetor drain hoses.
 

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I have a 1980 Custom and the petcock is a one piece sealed unit. Should I try to drill out the rivits that hold it together or not?
 

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Don't know if you should or not, but the "rivets" are actually alloy pins staked (smashed) to form a "head". After carefully drilling them out, a hole (each) will have to be drilled quite precisely and tapped, perhaps for a 4-40 thread (US) machine screw to reassemble. I use the dimple in the top of the staked pin to guide a smaller pilot drill into the valve body to later center my 4-40 tap drilling task. It's been done by some members, but it is tricky. I'm speaking of the repair of a vacuum fuel tap, if yours is a simpler non-vacuum tap, replacement may be more practical.
 

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Am I safe to assume that I could put the assembly into my carb cleaner? The top gasket is disolved already. Is the plastic tube removable?
 

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If you are referring to putting the petcock in an ultrasonic, I wouldn't think that would be a problem. There isn't much inside other than a rubber disk with four holes and a wave washer. That is for the standard petcock, the vacuum ones are a little more complex, but it probably wouldn't hurt them either.



I have encountered some petcocks that had to be disassembled to clean. They were fully packed with hardend fuel and you couldn't even poke a wire into them. Depending on the model, some can be drilled completely thru and a machine screw and nut used to replace the staked stud. (rivet)



I have had good success removing the filter tube inside the tank using a Easy-out. Just get a medium sized one and using only your fingers, gently screw into the tube and pull out. Don't force the Easy-out in, it will expand the plastic tube and make things tighter. If the tube is the one on the petcock, I don't think it is removable.
 

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I was referring to the liquid carb cleaner. Did not know that there was a rubber piece inside. If I drill it appart, can that rubber piece be obtained?
 

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1. There is a rubber piece inside.

2. Carb cleaner (the good stuff in a gallon can) will ruin the rubber parts inside.

3. The rubber part is not available because the petcock is not supposed to be serviceable.



Carb cleaner is not likely to be necessary, I've not seen a petcock that crudded up. The usual problem with petcocks is that they either leak when operating the valve lever, or they leak all the time. On the vacuum operated petcocks the rubber disk inside can be flipped over and provide a substantial extended useful life without leaking. This does require the drilling out of the staked pins and tapping for new fasteners though, as previously mentioned. It is a finicky task and some have not had success.
 

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I will drill it appart. What about the gasket where the petcock meets the tank? Mine dissolved. Do you have to make one?



I also assume that there was no fuel filter on this bike. I already purchased an after market one.
 

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I took mine apart. It was seized in the ON position and broke off one of the rivets trying to free it up. The rubber piece inside with the four holes was a total mess. As far as I know you can't buy that piece anywhere so I replaced the whole petcock with a non vacuum type off eBay as a temporary solution. It worked great as long as I remembered to turn off the thing when I shut down the engine. Otherwise, sometimes one of the float valves will leak a little and let raw gas into a cylinder. I have since bought a used vacuum petcock.



It might be possible to repair one of these things IF you could find a piece of rubber with exactly the right thickness, and IF you could get the remains of the old rivets out cleanly, and IF you could thread the holes, and IF you were very, very lucky. Good luck.
 

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Got it appart!! It looks as though somone melted a candle in it! A solid waxy mess. I saw a gasket on e-bay, but do not know if it fits correctly. Still leaves me with the petcock to tank seal to find.



I took some pics. Post them later. BTW, this type of petcock is a vacuum one?
 

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The vacuum operated petcock has three ports or nipples in addition to the tank fitting.



1. fuel out to carbs (largest nipple)

2. vacuum supply from right side carb (outboard nipple, frontmost when installed on bike)

3. atmospheric air vent (inboard nipple, often the hose has been discarded or lost, is supposed to be routed to beneath and behind the engine)



It came on later models of the CX/GL, not sure, but from about 1981 on I think. I don't remember any gasket on the vacuum type petcocks, the ported rubber disk acts as the seal. There are some spring and washer components under the operating lever to facilitate rotation and maintain pressure on the rubber seal disk. The vacuum petcock has a vac diaphram "sandwich" on the opposite side, this part is rebuildable and parts were available last I knew.



In case this is confusing, on the vac petcock there are actually two independent valves, the manual lever, ON-OFF-RESERVE. And the vacuum diaphram operated valve that opens when pulled by engine intake vacuum, which is open or closed. It takes very little vacuum to operate these valves. Blowing gently into the atmospheric vent hose will also open the vac valve.
 

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I think the gasket you are referring to is just an O ring. I'm not sure of the size, but you can probably judge that from the petcock and tank fitting. Make sure you use Viton or equiv, that doesn't melt in gas.



I have attempted to make some of those disks with a piece of rubber some time back. If memory serves me, it didn't work well. Finding the right rubber and getting the holes exactly right may prove to be a challenge. If the disk is not crumbly, you may be able to flip it over and use the other side. Just do a good cleanup and make sure the disk and handle side are very smooth. Then add some Dow 111 sealant and see how long it lasts. I have been successful doing this.
 

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I drillewd out the flanges and look what I found!!!











I then tapped the holes with a 4x40 tap and installed the screws/washers and a drop of blue lock tite.







I was able to remove the plastic tube bu twisting slightly and pulling on it. Then I could dip it in the carb cleaner. BTW, it took two dippings and scraping with a small screw driver.
 

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Were you able to salvage the rubber disk? It looks sorta toasted.
 

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Were you able to salvage the rubber disk? It looks sorta toasted.


Not long ago there were at least two vendors that sold the rubber discs in both types. It's a fairly comon piece, check eBay.
 
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